Printed circuit boards prepared either from a copper clad laminate or from a laminate made by electroless plating followed by electroplating over a substrate followed by steps such as coating the laminate with a resist, exposure of the resist in accordance with a desired pattern, development, etching, etc., are well known in the art. Similarly, additive processes such as catalyzing a substrate in accordance with a desired pattern and then selectively electrolessly plating the catalyzed areas of the substrate in accordance with the desired pattern with copper generally followed by building up the copper layer by electroplating are also well known in the art. Still other known techniques include the vapor deposition of a metal on a substrate either in blanket form followed by selective etching by means of photoresist and the like or selectively vapor depositing a metal on the substrate through a mask are also known.
There has recently been a desire and a trend in the manufacture of printed circuit boards to avoid excessive etching; this is especially due to the environmental hazards of the acids generally used for etching as well as for waste materials formed as well as the loss of metal which is first deposited which must then be etched away. While the additive electroless plating processes avoid this problem, such plating processes have problems of their own with regard to the handling of the various plating solutions that must be employed as well as in the cost involved in the various applicable photoresist and imaging techniques. The inventors of the present invention have surprisingly and unexpectedly discovered a simple method for preparing a printed circuit board, or for that matter any metallic pattern on a substrate, by means of sputtering a desired catalytic metal on a surface having a pattern thereon formed from an ink in a manner so as to result in the selective deposition of a metal on the surface in accordance with the negative of the pattern when treated in an electroless plating solution.